1. Field of the Invention
The present invention relates to a display device and a driving method thereof, and particularly to an organic light emitting device and a driving method thereof.
2. Discussion of the Background
A hole-type flat panel display such as an organic light emitting device displays a fixed picture for a predetermined time period, for example for a frame, regardless of whether it is a still picture or a motion picture. As an example, when some continuously moving object is displayed, the object stays at a specific position for a frame and then stays at a next position to which the object was moved after a time period of a frame in a next frame, i.e., movement of the object is discretely displayed. Since an afterimage is maintained within one frame, the motion of the object is displayed as continuous when it is displayed through the above-noted method.
However, when a user views the moving object on the screen, since the user's eyes continue to move as the object moves, screen displaying appears blurred by the mismatched displaying with the discrete displaying method by the display device. For example, assuming that the display device displays that an object stays at a position A in the first frame and it stays at a position B in the second frame, the user's eyes move along the object's expected moving path from the position A to the position B in the first frame. However, the object is not actually displayed at intermediate positions other than the positions A and B.
Resultantly, the object appears blurred since the luminance sensed by the user during the first frame is acquired by integrating the luminance of pixels on the path between the positions A and B, that is, the average of the luminance of the object and the luminance of the background.
Since the degree of blurring of the hole-type display device is in proportion to the time for the display device to maintain displaying, an impulse drive method for displaying the image for a predetermined time within one frame and displaying black for the rest of the time has been proposed. In this method, since the time for displaying the image is reduced to decrease the luminance, a method for increasing the luminance during the time of displaying or displaying an intermediate luminance with a neighboring frame other than black has been proposed. However, this method increases power consumption and increases drive complexity.
A pixel of the organic light emitting device includes an organic light emitting element and a thin film transistor (TFT) for driving the organic light emitting element, and when they are operated for a long time, the threshold voltage is varied so that the expected luminance may not be output, and when the characteristic of a semiconductor included in the thin film transistor is not uniform in the display device, luminance deviation between the pixels may occur.